Novice questions

Novice questions

[Jose Luis Zabalza]

Hello all

I'm trying write some code into barebox and  I have seen things that
caught my attention.

1.- Modules on barebox. lsmod, insmod commands, EXPORT_SYMBOL() macro.
What is the purpouse of these ? Modules have no means less memory
footprint ;-??
2.- usb command is on drivers/usb/usb.c file. What is the reason why
it is not on commands dir?
3.- What is the purpouse of usb command. Discover devices but after I
can't read because I have not drivers associates to them. Actually, is
there any way to read them?
4.- Does anyone use the usb for anything other than firmwarize the
device with DFU?

Thanks in avance

-- 
jlz.3008  a t  gmail.com
Linux Counter 172551

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Re: Novice questions

[Robert Schwebel]

On Fri, Jul 02, 2010 at 05:03:27AM +0200, Jose Luis Zabalza wrote:
> I'm trying write some code into barebox and  I have seen things that
> caught my attention.
>
> 1.- Modules on barebox. lsmod, insmod commands, EXPORT_SYMBOL() macro.
> What is the purpouse of these ? Modules have no means less memory
> footprint ;-??

There are people out there who want to be able to add functionality
later. Think about a product which was delivered in large quantities;
then you decide that you need a new functionality in the bootloader.
Modules make a nice interface for doing so.

rsc
-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
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Re: Novice questions

[Sascha Hauer]

Hello Jose,

On Fri, Jul 02, 2010 at 05:03:27AM +0200, Jose Luis Zabalza wrote:
> Hello all
> 
> I'm trying write some code into barebox and  I have seen things that
> caught my attention.
> 
> 1.- Modules on barebox. lsmod, insmod commands, EXPORT_SYMBOL() macro.
> What is the purpouse of these ? Modules have no means less memory
> footprint ;-??

We have modules support because we can ;)

I haven't used it in production yet, but there are usecases for it. I'm
currently porting UBI to barebox and it turns out to be quite huge
(~40k). You normally do not need UBI support for normal booting, but you
need it for updating UBI images. So you could make a module from it and
load it on demand.

> 2.- usb command is on drivers/usb/usb.c file. What is the reason why
> it is not on commands dir?

Some commands are in other directory because they are close to a
particular framework. We could move it to commands though.

> 3.- What is the purpouse of usb command. Discover devices but after I
> can't read because I have not drivers associates to them. Actually, is
> there any way to read them?

You probably tried an USB memory stick. These are not yet supported.
Barebox currently only supports USB network adapters.

> 4.- Does anyone use the usb for anything other than firmwarize the
> device with DFU?

Yes, for networking on boards which do not have a NIC, like the Beagle
Board.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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